The present invention relates to torque-measuring and torque-indicating wrenches and has particular application to such wrenches of the bending-beam type.
Bending beam torque wrenches typically include a resilient beam and a rigid reference beam fixedly secured together at a work-engaging end of the tool. When torque is applied to a workpiece by application of force at a handle end of the resilient beam, the resilient beam deflects an amount which varies as a function of the torque applied. This deflection results in a relative movement between the resilient beam and the reference beam, the distal end of which is free, this relative movement being visually observable with the use of suitable scale indicia, or being detected by suitable sensors.
Another type of torque wrench disclosed, for example, in copending U.S. application Ser. No. 09/118,873, filed Jul. 20, 1998, utilizes two rigid beams with a spring coupling between the ends thereof remote from the workpiece, the torque being coupled from one beam to the other through the spring mechanism, which also accommodates relative displacement of the beams to indicate the magnitude of the torque.
These prior types of torque wrenches have been relatively costly and/or have required that the beams be relatively large and bulky in order to provide the requisite deflection while, at the same time, accommodating transmission of the desired range of torque.
It is a general object of the invention to provide an improved torque wrench which avoids the disadvantages of prior wrenches while affording additional structural and operating advantages.
An important feature of the invention is the provision of a bending beam-type torque wrench which is of relatively small size and weight and of relatively simple and economical construction.
In connection with the foregoing feature, another feature of the invention is the provision of a torque wrench of the type set forth, which produces a torque measurement substantially unaffected by a user""s hand-hold position on the wrench.
Certain ones of these and other features of the invention may be attained by providing a torque wrench comprising: a resilient beam having a work-engaging end and a handle end, a reference beam having first and second ends coupled to the resilient beam respectively adjacent to the work-engaging and handle ends, and measurement apparatus disposed between the first and second ends and responsive to deflection of the resilient beam relative to the reference beam for providing an indication of the amount of torque causing the deflection.
Other features of the invention may be attained by providing a torque wrench of the character described, which includes a handle housing enclosing the beams along substantially their entire lengths and fixed to the resilient beam only adjacent to the handle end.
The invention consists of certain novel features and a combination of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the details may be made without departing from the spirit, or sacrificing any of the advantages of the present invention.